1. Field of the Invention
The present invention relates to an engine control apparatus having engine control modes including at least a high output mode and an output restricted mode.
2. Description Related Art Statement
Generally, a vehicle such as an automobile preferably has both excellent fuel economy performance and driving performance (acceleration response), but it is hard to achieve a vehicle which is provided with both of them. Thus, a technology is known in which a plurality of control modes including a standard normal mode, an economy mode for reducing fuel consumption, and a power mode for increasing output are set so that a driver can select one of the control modes through an operation such as a switching to provide both of fuel economy performance and driving performance to a vehicle.
For example, Japanese Patent Application Laid-Open No. 5-332236 discloses a technology for selecting an air-fuel ratio map and an ignition timing map which correspond to a control mode (one of economy mode and power mode) selected by a driver so as to perform fuel injection control and ignition timing control based on the selected maps.
Japanese Patent Application Laid-Open No. 5-65037 discloses a technology for improving both fuel economy performance and driving performance (acceleration response) by setting the characteristics of opening-degrees of an electronic controlled throttle and characteristics of transmission of an automatic transmission for each control mode (economy mode and power mode) in association with each other, and performing the throttle opening-degree control and the transmission control in accordance with these characteristics.
However, in the above technologies disclosed in the documents, at a start of a vehicle, if a driver of the vehicle selects a control mode such as an economy mode in which an output is restricted to reduce fuel consumption, an engine of the vehicle is operated under a high load, so that a hill start of a vehicle on a steep grade for example in an economy mode sometimes results in an insufficient torque, and an excellent starting performance cannot be attained.
On the other hand, if a driver of the vehicle selects a control mode such as a power mode for increasing output at the start of a vehicle, a slight depression of an accelerator pedal leads to a considerable change of a driving torque, so that a start of a vehicle on level ground for example in the power mode in which an engine of the vehicle is operated under a low load sometimes results in a shock of a sudden start for the driver due to a rapid acceleration.
As a result, at a start in a restricted output mode such as an economy mode selected by a driver, there is a range that the driver feels an insufficient torque, while at a start in a high output mode such as a power mode, there is a range that the driver feels a shock of a sudden start due to an increased torque. In either mode at the start of a vehicle, an excellent driving performance cannot be attained.